Aircraft Observation of Ice-Nucleating Particles in Taiyuan, China

In November 2016, we measured the concentration of ice nucleating particles in the lower troposphere from aircraft in Taiyuan, China. Aerosol samples were collected by electrostatic precipitators onboard the aircraft at altitudes up to 5.5 km. The number of INP in these samples, which are actived in the deposition and condensation modes at temperatures from −17 to −26ºC and supersaturations with respect to ice between 8% and 24%, were analyzed after collection using a static vacuum water vapor diffusion chamber. This chamber was based on the principles of the static vacuum vapor diffusion chamber FRIDGE (Frankfurt Ice Nuclei Deposition Freezing Experiment). Vertical profile of IN concentration shows that at a given level, there is large spatial and temporal variation in IN concentration. Spatial variation in IN concentration was observed in the range 0 to 18 L^-1 with an average of 6.22 L^-1 at highest ice supersaturation. Our observation shows that there is a significant increase in IN concentrations with supersaturation over ice. There is no significant correlation between INP concentration and aerosol number concentration in high altitude when there is no obvious weather process. The direction of the air mass has a significant effect on the concentration of high-altitude INP. In this study, when the air mass came from the south, the INP concentration was twice as low as that of the northern air mass.